水-温循环作用下千枚岩的动态拉伸特性

为研究水-温耦合作用下0°层理倾角千枚岩的动态拉伸特性变化规律，分别对3组试样进行0、1、3、5、7、8、11次温度循环自然降温、温度循环冷水降温、干湿循环后，采用霍普金森杆试验装置对0°层理倾角千枚岩试样开展动态巴西劈裂试验，从动态拉伸应变曲线、动态峰值抗拉强度、动态弹性模量、能量分析与宏观破坏5个角度研究水、温劣化条件下千枚岩的动态拉伸特性。结果表明：千枚岩应力应变曲线包括极速弹性变形阶段、屈服变形阶段、破坏变形阶段；随着水-温循环次数的增加，千枚岩应力-应变曲线极速弹性变形阶段逐渐缩短，屈服变形阶段的应变增长率不断增大；千枚岩动态峰值抗拉强度呈负指数函数关系变化，耗散能比不断减小；水-温耦合条件下，千枚岩峰值抗拉强度、耗散能比普遍小于温度循环自然降温时；动态冲击下，千枚岩发生贯穿层理的张拉破坏，主要破碎为2块；随着水-温循环次数的增加，千枚岩主碎块发生沿层理面的张拉与穿层理面的剪切复合破坏，千枚岩碎块的平均尺寸不断减小；温度循环冷水降温条件下，千枚岩碎块的平均尺寸更小，且降幅最为显著。

Dynamic tensile characteristics of phyllite under water-temperature cycle conditions

In order to study the variation pattern of dynamic tensile properties of phyllite under the coupling effect of water temperature, three groups of samples were subjected to 0, 1, 3, 5, 7, 8 and 11 times of temperature cycle natural cooling, temperature cycle cold water cooling and dry-wet cycle respectively. The dynamic Brazilian splitting test samples was carried out by Hopkinson bar test device. The dynamic tensile properties of phyllite under water and temperature deterioration were studied from five aspects: dynamic tensile strain curve, dynamic peak tensile strength, dynamic elastic modulus, energy analysis and macroscopic failure. It is found that the stress-strain curve includes extremely fast elastic deformation stage, yield deformation stage and failure stage. With the increase of the number of water temperature cycles, the extreme elastic deformation stage of stress-strain curve gradually decreases, and the strain growth rate in the yield deformation stage increases continuously. The dynamic peak tensile strength of phyllite shows a negative exponential function distribution, and the dissipation energy ratio decreases continuously. Under the condition of water temperature coupling, the peak tensile strength and dissipation energy ratio of phyllite are generally smaller than those of temperature cycle natural cooling. Under the dynamic impact, the phyllite occurs tensile failure throughout the bedding, mainly broken into 2 pieces. With increase of the number of water temperature cycles, the main phyllite fragments undergo tensile failure along the bedding plane and shear failure across the bedding plane, and the average size of the phyllite fragments decreases continuously. Under the condition of temperature circulating cold water cooling, the average size fragment is smaller and the decrease is the most significant.